Significance: The 1999 Institute of Medicine Report (IOM) estimated that preventable medical errors lead to 44,000 - 97,000 deaths in the United States each year (IOM report), greater than the annual number of US deaths from motor vehicle accidents or from breast cancer. The issue of medical errors is significant for living donor liver transplantation (LDLT) because LDLT is one of the most complex processes and systems of care in healthcare and, as a result, is at increased risk for medical errors. Most importantly, LDLT involves a healthy donor who is undergoing an extensive surgery, who derives no benefit from the procedure yet, incurs the risk of preventable complications. Hence, it is imperative that such potential risks be identified and prevented. Innovation: This study builds on the strength of two unique collaborations: 7 NUTORC a multidisciplinary collaboration of investigators which brings together expertise in safety research (Drs. Woods and Holl) and extensive clinical knowledge LDLT (Drs. Ladner, Abecassis and Skaro);and the 7 A2ALL Deux Study which involves nine large LDLT centers and will provide sufficient numbers of LDLT to achieve adequate power to study the effectiveness of the solutions designed to reduce medical errors and preventable complications. This study is novel and innovative, because it seeks to shift the paradigm of response to medical errors to a proactive approach of assessing and improving the safety of systems and processes to prevent medical errors in LDLT before they occur. This study will apply methods from other high risk industries to generate new and important information about LDLT safety not obtainable through other methods. LDLT provides an excellent opportunity to fully assess medical errors and preventable complications as there is little risk of confounding by donor co-morbid conditions. Approach: The NIH embarked on the adult-to-adult living donor liver transplantation (A2ALL) initiative in an effort to address outcomes in living donors and recipients of living donor organs. This proposed study is an approved Ancillary Study of the A2ALL Deux and will involve seven of the largest transplant centers in the United States, all part of A2ALL. This study will: 1) Proactively and systematically identify medical errors and preventable complications in LDLT through a) review of LDLT medical records and A2ALL Data Safety Monitoring Board reports, b) review of LDLT processes and systems of care using a Failure Mode Effects Analysis and Web-based Debriefings;2) Design and implement safety solutions for the LDLT processes and systems of care at high risk for medical errors and preventable complications at four participating A2ALL transplant centers;3) Evaluate the effectiveness of the implemented solutions, by comparing medical errors and preventable complications pre- post- solution implementation and between the participating centers and A2ALL center controls. PUBLIC HEALTH RELEVANCE: Medical errors and preventable complications are prevalent in healthcare. The issue of medical errors is particularly important for living donor liver transplantation (LDLT) because LDLT is one of the most complex processes and systems of care in medicine and, as a result, is at increased risk for medical errors. Most importantly, LDLT involves a healthy donor who is undergoing a procedure for which he/she will derive no medical benefit but is exposed to potential medical errors. NIDDK funded the Adult to Adult Living Liver (A2ALL) Cohort Study to assess Living Donor Liver Transplantation (LDLT). Across four participating A2ALL transplant centers, this A2ALL Ancillary Study will: 1) conduct a systematic assessment of medical errors and preventable complication in LDLT, 2) assess the weaknesses in the LDLT systems and processes of care that contribute to their occurrence, 3) design and implement safety solutions to address medical errors and preventable complications, and 4) evaluate the impact of the implemented solutions, pre- post- solution implementation and in comparison with 3 A2ALL transplantation center controls 4) in LDLT will be conducted across four high volume LDLT centers.